FreeLists / az-observing / [AZ-Observing] Re: NGC 6166 & Company

[BillFerris@xxxxxxx]

Jack Jones wrote:
> Any season's fine with me. I observed NGC 6166 also (on July 1) at 65
> and 200x and drew the same southerly corona of 5 stars it appears to be
> at the tail end of, as in your drawing. I'd say its peculiarity comes
> from the fact that it is in the process of gobbling up all its little
> 'friend' galaxies around it. Looked featureless in my scope tho. MCG
> 7-34-50 is 14.8, pretty good for a 10-inch. Musta been hi power in dark
> skies maybe? :-) MCG 7-34-48 at 'only' mag 14.3 is what you call
> PGC58244 and right beside it ala M31/M110, but I don't show it in the
> 14.5". Hercules was sinking fast at the time, so I'll have to revisit.
> 
Just to follow up on my observation of MCG 7-34-50, the 14.8 magnitude value 
is lifted from MegaStar 5. NED lists a 15.3 magnitude (presumably blue or 
photographic) but all the photometric references are 2MASS. Anyway, while 14.8 
magnitude is faint, the sub-arcminute size of the galaxy yields a surface 
brightness of 21.4 mag./arcsec.^2.

That's a fairly unremarkable surface brightness. but the small size means the 
SB can quickly shoot through the floor when the seeing deteriorates. It's my 
guess that variable seeing resulted in detection only about 40% of the time 
with my scope. If either the seeing or transparency had been worse, 
fuhgetaboutit.

Regards,

Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net


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